The present invention relates to catalysts for oxidizing exhaust-gas components at temperatures between 200 and 1000° C., which catalysts preferentially oxidize hydrocarbons before carbon monoxide.
Precious metal catalysts containing 0.1 to 5 wt. % precious metal, based on the oxide carrier mass, exhibit a good to very good oxidation effect at temperatures above 200° C., particularly above 300° C. The stability of such systems with respect to high temperatures, particularly above 850° C., is improved by higher precious metal loads.
Mixed oxide catalysts, which completely eliminate precious metal additives, can exhibit sufficient oxidation activity at low volume velocities. In general, the response temperatures for the catalytic activity lie in part significantly above those of precious metal catalysts. The stability with respect to high temperatures is generally poorer than in precious metal catalysts. In addition, non-precious metal catalysts react rather selectively with carbon monoxide and are less suitable for the combustion of hydrocarbons.